TY - JOUR
T1 - Proteolytic activation of proteose peptone component 3 by release of a C-terminal peptide with antibacterial properties
AU - Pedersen, Lise Refstrup Linnebjerg
AU - Hansted, J.G.
AU - Nielsen, Søren Bang
AU - Petersen, T.E.
AU - Sørensen, U.S.
AU - Otzen, D.
AU - Sørensen, E.S.
N1 - MEDLINE® is the source for the MeSH terms of this document.
PY - 2012/6/1
Y1 - 2012/6/1
N2 - The milk protein proteose peptone component 3 (PP3, also known as lactophorin) is a small phosphoglycoprotein, which is exclusively expressed in the lactating mammary gland. A 23-residue synthetic peptide (lactophoricin, Lpcin S), corresponding to the C-terminal amphipathic α-helix of PP3, has previously been shown to permeabilize membranes and display antibacterial activity. Lactophorin readily undergoes proteolytic cleavage in milk and during dairy processing, and it has been suggested that PP3-derived peptides are part of milk's endogenous defense system against bacteria. Here, we report that a 26-residue C-terminal peptide (Lpcin P) can be generated by trypsin proteolysis of PP3 and that structural and functional studies of Lpcin P indicate that the peptide has antibacterial properties. The Lpcin P showed α-helical structure in both anionic and organic solvents, and the amount of α-helical structure was increased in the presence of lipid vesicles. Oriented circular dichroism showed that Lpcin P oriented parallel to the membrane surface. However, the peptide permeabilized calcein-containing vesicles efficiently. Lpcin P displayed antibacterial activity against Streptococcus thermophilus, but not against Staphylococcus aureus and Escherichia coli. The PP3 full-length protein did not display the same properties, which could indicate that PP3 functions as a precursor protein that upon proteolysis, releases a bioactive antibacterial peptide.
AB - The milk protein proteose peptone component 3 (PP3, also known as lactophorin) is a small phosphoglycoprotein, which is exclusively expressed in the lactating mammary gland. A 23-residue synthetic peptide (lactophoricin, Lpcin S), corresponding to the C-terminal amphipathic α-helix of PP3, has previously been shown to permeabilize membranes and display antibacterial activity. Lactophorin readily undergoes proteolytic cleavage in milk and during dairy processing, and it has been suggested that PP3-derived peptides are part of milk's endogenous defense system against bacteria. Here, we report that a 26-residue C-terminal peptide (Lpcin P) can be generated by trypsin proteolysis of PP3 and that structural and functional studies of Lpcin P indicate that the peptide has antibacterial properties. The Lpcin P showed α-helical structure in both anionic and organic solvents, and the amount of α-helical structure was increased in the presence of lipid vesicles. Oriented circular dichroism showed that Lpcin P oriented parallel to the membrane surface. However, the peptide permeabilized calcein-containing vesicles efficiently. Lpcin P displayed antibacterial activity against Streptococcus thermophilus, but not against Staphylococcus aureus and Escherichia coli. The PP3 full-length protein did not display the same properties, which could indicate that PP3 functions as a precursor protein that upon proteolysis, releases a bioactive antibacterial peptide.
UR - http://www.scopus.com/inward/record.url?scp=84862072352&partnerID=8YFLogxK
U2 - 10.3168/jds.2011-4837
DO - 10.3168/jds.2011-4837
M3 - Journal article
C2 - 22612919
AN - SCOPUS:84862072352
SN - 0022-0302
VL - 95
SP - 2819
EP - 2829
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 6
ER -